Recently, with the development of automobile technology, much attention has been given to environmentally friendly vehicles including electric vehicles powered by electric motors and fuel cell vehicles powered by electricity from fuel cells, as well as hybrid vehicles powered by electric motors and engines.
When the environmentally friendly vehicle is operating in EV mode, that is, in an operating condition in which the vehicle is driven by the electric motor, noise generated by the vehicle while driving may be excessively low and much smaller than that from an internal combustion engine such that it may be difficult for pedestrians (especially, those who are blind or visually impaired) to perceive approach of the vehicle, causing a safety accident.
To address this issue, a virtual engine sound system (VESS) that emits a virtual engine sound to the outside of the vehicle through a speaker to allow pedestrians to be aware of the vehicle approaching has been mounted in the environmentally friendly vehicles.